summaryrefslogtreecommitdiffstats
path: root/Documentation/usb/dma.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/usb/dma.txt')
-rw-r--r--Documentation/usb/dma.txt11
1 files changed, 6 insertions, 5 deletions
diff --git a/Documentation/usb/dma.txt b/Documentation/usb/dma.txt
index e8b50b7..cfdcd16 100644
--- a/Documentation/usb/dma.txt
+++ b/Documentation/usb/dma.txt
@@ -6,8 +6,9 @@ in the kernel usb programming guide (kerneldoc, from the source code).
API OVERVIEW
The big picture is that USB drivers can continue to ignore most DMA issues,
-though they still must provide DMA-ready buffers (see DMA-mapping.txt).
-That's how they've worked through the 2.4 (and earlier) kernels.
+though they still must provide DMA-ready buffers (see
+Documentation/PCI/PCI-DMA-mapping.txt). That's how they've worked through
+the 2.4 (and earlier) kernels.
OR: they can now be DMA-aware.
@@ -62,8 +63,8 @@ and effects like cache-trashing can impose subtle penalties.
force a consistent memory access ordering by using memory barriers. It's
not using a streaming DMA mapping, so it's good for small transfers on
systems where the I/O would otherwise thrash an IOMMU mapping. (See
- Documentation/DMA-mapping.txt for definitions of "coherent" and "streaming"
- DMA mappings.)
+ Documentation/PCI/PCI-DMA-mapping.txt for definitions of "coherent" and
+ "streaming" DMA mappings.)
Asking for 1/Nth of a page (as well as asking for N pages) is reasonably
space-efficient.
@@ -93,7 +94,7 @@ WORKING WITH EXISTING BUFFERS
Existing buffers aren't usable for DMA without first being mapped into the
DMA address space of the device. However, most buffers passed to your
driver can safely be used with such DMA mapping. (See the first section
-of DMA-mapping.txt, titled "What memory is DMA-able?")
+of Documentation/PCI/PCI-DMA-mapping.txt, titled "What memory is DMA-able?")
- When you're using scatterlists, you can map everything at once. On some
systems, this kicks in an IOMMU and turns the scatterlists into single
OpenPOWER on IntegriCloud